The Wrestling Moves List will no doubt have the double leg takedown on it since you end up in a great position for many takedown transitions. The double leg takedown is essentially getting control of your opponent from a standing position in order to take them to the mat by grabing both of his legs and moving his center of gravity from him to you. The Doubletime to the Mat post goes through the basics of a finding yourself in a double leg basic position and what options you have to convert that into a takedown.
To perform a double let you can either perform a Snatch or you can use a penetration step.
Step 1: Perform a Setup. (clear the hands, control the head, change your opponents center of gravity)
Step 2: Perform a Penetration Step.
Step 3: Place your head to either side of your opponent. Takedown conversions will be described as either towards you or away from you. Towards you indicates the side your head is on and away from you indicates the opposite side. The head to the inside is possible however your head will create space between you and your opponent and will make it difficult for you to pull your opponent in tight and transfer his center of gravity.
Step 4: Push your chest up against your opponents thighs and hips. The less space you have the better control you will have over your opponents strong leg muscles.
Step 5: Wrap your arms around your opponents legs and place your hands at the back of the knees. The more you can pull at the knees the easier it will be to collapse your opponents legs and prevent a sprawl defensive move.
At this point you will be in the basic leg setup position to move on to Doubletime to the Mat.
The double leg takedown is a great takedown for a fast striker. If you have an explosive forward strike this is the takedown for you.
Here is a video showing a double leg shot converting it into a takedown using a Tackle.